1. Field of the Invention
The present invention relates to a developing device and an image forming apparatus.
2. Description of Related Art
In conventional image forming apparatuses such as printers, photocopiers, facsimile machines, and multifunction devices, for example, in printers, a surface of a photosensitive drum is charged with a charging roller and exposed with an LED head to form an electrostatic latent image, which is developed with a developing device thereafter, resulting in a toner image.
In the developing device, where toner serving as developer, which is thinly layered on a developing roller, is electrostatically attached thereto to form a toner image, the toner image is then transferred to a paper with a transfer roller, achieving image formation, in other words, executing printing. The toner remaining on the photosensitive drum after the transfer operation is removed with a cleaning device.
The developing roller is provided with a developing blade as a restricting member for restricting a toner layer supplied to the developing roller by bringing a front end of the developing blade in contact with the developing roller, and sealing units for preventing toner from leaking from at both end sides of a toner supply roller for supplying the developing roller with the toner by bringing both ends of the toner supply roller in contact with both ends of the developing blade member. An example of related art is Japanese Patent Application Publication No. 2002-108089.
In the conventional developing device, however, the sealing units are provided in contact with both ends of the developing blade member, thereby being sometimes curled up by the developing blade member during assembly of the developing blade member, resulting in gaps between the developing blade member and the sealing units, from which the toner undesirably leaks.